The first of Maxwell’s equations is Gauss’s law for the electric field, which we first encountered in Section 16-6. It states that the net electric flux through a closed surface (called a Gaussian surface) is proportional to the total amount of electric charge enclosed within that surface:
In this equation we’ve added a subscript \(E\) to remind us that the quantity on the left-hand side is the flux of the electric field \(\vec{E}\).